1. Field of the Invention
The present invention relates generally to a disc device for recording or reproducing information on or from business image files, computer data files, or other editable data files, or for recording or reproducing information on or from a disc for use in an image player. In particular, the present invention relates to a disc device having a plurality of heads for recording or reproducing image information or the like.
2. Description of the Prior Art
In recent years, development of a disc device capable of digitally recording or reproducing dynamic images such as, for example, NTSC composite signals is being increasingly pursued by increasing the device-wide transfer rate. To this end, information to be recorded is divided into plural pieces of information, and divided information is combined for reproduction with the simultaneous use of a plurality of heads.
Japanese Laid-open Patent Publication (unexamined) No. 1-118246, filed on Oct. 30, 1987, discloses a disc device in which an increased transfer rate is obtained by recording or reproducing information with the simultaneous use of eight heads.
This disc device accommodates a disc having an information area divided radially equally into eight information regions. The disc device has four sliders each having two heads mounted thereon. Two of the sliders can move in a first direction radially of the disc and are disposed opposite to each other with respect to the center of the disc, while the other two sliders can move in a second direction radially of the disc and perpendicular to the first direction and are disposed opposite to each other with respect to the center of the disc. One of the two heads mounted on each slider is intended to record or reproduce information on or from one of four outer information regions, while the other head is intended to record or reproduce information on or from one of four inner information regions.
In such a conventional disc device, the heads are required to be reduced in size in order to avoid interference between the heads movable in the first direction and those movable in the second direction at an innermost circumferential area of the disc. Conversely, the use of heads of an ordinary size results in the interference between the heads at the innermost circumferential area and, hence, the problem arises that such an area cannot be used as the information area.
Furthermore, because the disc device must be so designed that the heads can move as far as the outer information area in both the first and second directions, the problem arises that the disc device inevitably becomes large in both of the directions. In applications where the use of a disc having a diameter of 300 mm is desired to achieve large capacity recording or to prolong the recording time, the width of the disc device exceeds 435 mm no matter which direction is chosen to be a direction widthwise of the disc device. Accordingly, the problem arises that installation of the disc device on a 19-inch rack which is inevitably required for business purposes is impossible.